Lubricating oil composition



Patented Dec. 23, 1952 LUBRICATING OIL COMPOSITION Richard W. Mertes, Los Angeles, Calif., assignor to Union Oil Company of California, Lcs Angeles, Calif., a corporation of California No Drawing. Application January 17, 1949, f Serial No. 71,402

15 Claims. 1 This invention relates to lubricating oils. This application is a continuation-in-part of my co-pending application Serial No. 658,879, filed April 1, 1946, now abandoned, which was a con- ,tinuation-in-part of the then co-pending application Serial No. 458,459 filed September 15, 1942, now abandoned.

Primarily, the object of the invention is to produce mineral lubricating oils for internal combustion engines which possess a very high degree of detergent power for the removal of resinous and similar deposits from the piston skirts, piston rings and ring grooves of internal combustion engines.

In many internal combustion engines, especially diesel engines, where severe service conditions are encountered there is a stronger tendency than ordinarily to deposit on the piston skirts and upon the rings and in the ring grooves an objectionable amount of resinous and varnish-like materials. The deposition of these materials may be controlled and largely prevented, and to some extent may be removed after formation by the use of certain types of additives in the lubricating oil.

One form of additive which possesses some merit is metal soaps of oil-soluble petroleum sulfonic acids obtained by the sulfonation of mineral oil fractions, such as mineral lubricating oil fractions. The particular sulfonic acids employed are the so-called mahogany acids, that is, the oil-soluble sulionic acids produced in the process as distinguished from the water-soluble, so-called green acids, although it is possible sometimes to use a mixture of both the mahogany acids and green acids because of the fact that mahogany acid soaps possess some solubilizing properties for the green acid soaps when added to mineral lubricating oil. These sulfonic acids are produced according to well known processes by treating the oils with strong or fuming sulfonic acid or chlorsulfonic acid. The green acids are separated in the sludge, and the mahogany acids may be recovered as soaps by introducing the desired base material, for example, lime or calcium hydroxide to produce the corresponding metal soap in the treated oil. 01', where the mixed soaps are desired, the whole batch may be treated with the desired base material. Or, the sodium soap may be recovered by any well known or preferred method and a desired soap prepared therefrom in any known manner and combined with oil to yield a suitable concentrate of the metal sulfonate in a petroleum oil fraction. V

In preparing the final lubricating oil the desired sulfonate, or a concentrate thereof, is added tothe oil and dissolved therein by the simple expedient of admixture and agitation, to produce the desired concentration. The percentage of soap in the final oil is ordinarily in the neighborhood of 1% to 2% but may vary from about 0.5% to 3% or more as desired or required.

The particular improvement of this invention resides in further treating the recovered sulfonate or sulionate concentrate with a metal salt of a weak inorganic acid for the purpose of increasing the detergent properties and in some cases increasing the anticorrosion characteristics of the soap (sulfonate). I have found that the soap or soap concentrate may have combined therewith a weak acid salt by a more or less simple mixing and heating operation and the resulting product may be filtered without removing the solubilized weak acid salt. It is not clear whether a loose complex is formed between the sulfonate and the weak acid salt, or whether the sulfonate simply serves as a solubilizing agent to hold the weak acid salt in solution in the oil. Since the oil solution of the sulfonate to which the salt has been added exhibits the Tyndall effect and since the number of moles of salt per mole of sulfonate can be made larger than would normally be expected for any known type of complex other than a loose addition compound, the sulfonate very likely holds the inorganic salt in solution in the form of a colloidal suspension. For the purposes of this description, however, the modified sulfonate will be referred to as a sulfonate-weak acid salt complex, or more specifically as a complex of a metal sulfonate and a metal salt of a weak inorganic acid.

By the term weak acid or weak inorganic acid as used herein it is meant to include the inorganic acids having a dissociation constant (or in the case of dibasic and tribasic acids a dissociation constant for the primary hydrogen) less than about 1 10- The term weak acid salt or metal salt of a weak inorganic: acid is used herein to define the metal salts of such weak acids, 1. e., those having a dissociation constant or a dissociation constant for the primary hydrogen less than 1 l0- In preparing the improved oils of this invention, the desired oil-soluble metal sulfonate has the desired weak acid salt solubilized in it by varying procedures, depending on the nature of the salt. For example, in a preferred method, an oil concentrate of the oil-soluble metal sulfonate is heated to somewhat elevated temperatures, e. g., 150 F. to 450 F. or even 500 and maintained at this temperature while an aqueous solution or slurry of the weak acid salt is added slowly and with vigorous agitation. The 61vvated temperature is maintained for a period of about minutes or an hour or even longer, say two hours, to insure vaporization of all of the free water, i. e., water which would separate on cooling, and to effect such reaction as may take place in solubilizing the salt. At the completion of the heating period the product is filtered to remove any residual material which has not been solubilized. This method is particularly applicable to weak acid salts which can be dissolved directly in water to give fairly concentrated solution, though for less soluble salts aqueous slurries may be used.

In carrying out the preparation of the complex and dehydration (which latter term will be employed to mean removal of free water, i. e., water which separates as a separate phase) by admixing an aqueous solution of the salt and an oil solution of the sulfonate at the lower temperatures indicated above, the desired water removal may be accomplished by operating at reduced pressures. This method is particularly adaptable to salts which are not stable in aqueous solutions at the higher temperatures indicated. In this manner complexes have been prepared at temperatures as low as 120 F. Thus complexes of this invention may be prepared at temperatures between 120 and 500 F. although temperatures in the range of 200 F. or

250 F. to 450 F. are more conveniently employed and are preferred. Also, lower temperatures may be employed if a carrying agent, such as a low boiling diluent, is employed during the heating and dehydrating operations. Such carrying agents as toluene, naphtha, and the like distill from the mixture together with the water.

In cases where the desired salt is substantially insoluble in water, provided its constituent acidic and basic portions are themselves adequately stable, it is convenient to form the salt in situ from its acidic and basic progenitors. For example, in solubilizing calcium arsenate an oil solution of calcium sulfonate may be reacted as described above first with an aqueous slurry of calcium hydroxide and then with a stoichiometrically equivalent aqueous solution of arsenic acid. Similarly, in preparing the carbonate and bicarbonate complexes the metal sulfonate is first reacted with the hydroxide of the desired metal and the resulting product is blown with carbon dioxide to convert the hydroxide into the carbonate or bicarbonate. The resulting mixture is dehydrated and filtered. The above described operations result in a concentrate containing the desired modified sulfonate.

The amount of weak acid salt to be employed may vary appreciably depending upon the particular salt to be used, but will in general approximate 5% to about 75% of the original sulfonate. Apparently 75% is normally more than is necessary and perhaps more than is desired, but it appears that up to about of the weak acid salt calculated on the sulfonate content is desirable. This amount will vary with the particular sulfonate and the particular weak acid salt employed. The proportion of weak acid salt to be employed is probably better indicated on an equivalency basis. Calculated on this basis the amount of, weak acid salt to be complexed will vary between about 0.2 and 3 chemical equivalents of weak acid salt to 1 equivalent of the metal sulfcnate and preferably the ratio will be between 0.5 and 2 equivalents of the weak acid salt per equivalent of the metal sulfonate.

In employing the modified sulfonate in the oil, this ordinarily is done in the order of from about 1% to about 3.0% of an oil-free basis, although larger proportions may be used such as up to about 5% with correspondingly beneficial results, and larger proportions also may be used but with these larger proportions, such as around 7% or more, the improvement in the oil per given quantity of additive diminishes. There is improvement however, and amounts around 10% are desirable in modern heavy duty diesel engines, and amounts up to about 20% may be employed, the higher limit appearing to be snly that point at which the viscosity of the final oil becomes too great. On the lower side, benefits are obtainable down to as low as 0.5% and apparently correspondingly lower benefits are obtained with still lower proportions, e. g., 0.2% of the modified sulfonate.

The sulfonates which may be used in the preparation of the metal sulfonate-weak acid salt complexes include the oil-soluble mono and polyvalent metal salts of sulfonic acids. Thus the metal of the metal sulfonate may be alkali metal such as sodium, potassium or lithium; alkaline earth metal such as calcium, barium, strontium or magnesium; or a polyvalent metal such as lead, zinc, tin, aluminum, iron, cobalt, nickel, manganese, chromium, copper, silver, mercury, beryllium, and the like. The oil-soluble sulfonic acid salts of these metals are capable of solubilizing weak acid salts to form complexes, which complexes, when added to oil in the amounts indicated herein, greatly improve the service characteristics of the oil and particularly improve the detergency of the oil.

Metal salts of weak inorganic acids having an ionization constant less than 1 l0 which may be combined or complexed with the sulfonates to improve the detergency of the sulfonates in oil solution are those which may be solubilized by one of the methods described hereinabove and include the weak acid saltsof'any or" the metals indicated hereinabove as being useful in preparing the metal sulfonates. The derivatives of these metals which may be employed as modifying agents include the thiosulfates such as calcium thiosulfate, CaSzOz, sodium thiosulfate or the like; trithionates such as calcium trithionate, CaSsOc, sodium trithionate or other metal trithionates; tetrathionates such as calcium tetrathionate, (3343406; arsenates such as sodium arsenate, Na3ASO4; arsenites such as sodium arsenite, NazASOs; thioarsenates such as calcium thioarsenate, Ca(AsS3)2; thiocyanates such as calcium thiocyanate, Ca(SCN barium thiocyanate, Ba(SCN)2; antimonates such as calcium antimonate, Ca::(SbO4)2; antimonites such as sodium antimonite, NaSbOz; thioantimonites such as calcium thioantimonite, Ca(SbS2)-. cyanides such as nickel cyanide, Ni(CN)2; cyanates such as lead cyanate, Pb(CNO)2; sulfites such as calcium sulfite, sodium sulfite; phosphates, such as sodium phosphate, calcium pyrophosphate, (Ca2P2O1) chromates, such as lead chromate, lithium chromate; borates including the meta and tetraborates such as calcium metaborate, Ca(BO2)z; sodium tetraborate, NazBiOv, zinc borate, 3ZnO-2Bz0z; aluminates such as sodium aluminate, NaAlOz; stannates such as sodium stannate, NazSIlOa; plumbites such as sodium plumbite and calcium plumbite; carbonates such as sodium carbonate, potassium carbonate, calcium carbonate, copper carbonate, lead carbonate; bicarbonates such as sodium bicarbonate, calcium bicarbonate and, in fact, many other related metal salts of weak inorganic acids which may be solubilized in the manner described. It is to be understood that the specific compounds mentioned are only illustrative and that any of the above acid radicals may be combined with any of the above metals to form salts which are included within the scope of the invention. The metal carbonates and bicarbonates which, together with metal oxides and hydroxides, are normally considered as inorganic bases, are specifically claimed in my co-pending applications Serial No. 703,097 filed October 14, 1946 now issued as Patent No. 2,501,731, and Serial No. 726,224, filed February 3, 1947 now issued as Patent No. 2,501,732.

The method of preparing metal sulfonates is well known in the art and in most cases, particularly with the alkali and alkaline earth metal sulfonates, they may be prepared by direct neutralization of sulfonic acids with the desired metal base. Thus sulfonic acids may be neutralized with sodium hydroxide to form sodium sulfonates or with calcium hydroxide to form calcium sulfonates. Since sulfonic acids are generally recovered from oil solution, following their preparation by treatment of an oil such as a lubricating oil fraction with sulfuric acid, by extraction with sodium hydroxide or sodium carbonate, the sodium salt is the one generally available on the market. Generally, also, unless deoiling processes are resorted to the sodium salt will be associated with mineral oil where the mineral oil constitutes between 25% and 75% of the total. This sodium sulfonate concentrate in oil may be reconverted to sulfonic acids by treatment with sulfuric acid followed by water Washing to remove inorganic salts and excess acid and the sulfonic acids converted into the desired metal salt. This method would be employed in the preparation of potassium or lithium sulfonates, for example. However, in preparing any of the polyvalent metal sulfonates the sodium sulfonate can be reacted with a Water-soluble salt of the desired polyvalent metal to produce, by metathesis, the desired polyvalent metal sulfonate. The resulting sulfonate is washed free of inorganic salts with water. Thus, the calcium sulfonate can be prepared by metathesizing sodium sulfonate with an aqueous solution of calcium chloride. Similarly, a lead salt may be prepared by metathesizing sodium sulfonate with aqueous lead nitrate. If the sodium sulfonate employed was in oil solution the resulting polyvalent metal sulfonate will also be in oil solution and this oil solution may be employed directly in the complexing step with a weak acid salt.

The complexes of this invention may be prepared using a metal sulfonate and a metal salt of a weak acid where the metal of the sulfonate and of the weak acid salt is the same or different. Thus, a calcium sulfonate may be complexed with a calcium salt of a weak acid or with a different metal salt of a weak acid, as for example, with a sodium salt or lead salt. Desirable lubricating oil addition agents of the type herein described have been prepared where the metal is the same and where the metal is different.

As a modification of the described method of preparation of the modified sulfonates of this invention it is found that complex formation between the sulfonates and the weak acid salts is improved by carrying out the complexing operation with added glycerol. The eifect of the glycerol is not understod; however, it is observed that using about 5%, or at least within the range of about 1% to 10 or 15% of glycerol, based on the sulfonate concentrate in oil, solubilization of the weak acid salt occurs more rapidly than when glycerol is not present. Moreover, the amount of weak acid salt which becomes solubilized by the metal sulfonate sometimes may be increased by the use of glycerol as an activating agent for the reaction. Thus, in the case of weak acid salts which are dimcult to solubilize or complex by the method above described it is found that the addition of glycerol to the reaction mixture greatly facilitates the complexing. The use of glycerol is indicated particularly in the case of those compounds which are water-insoluble and must be complexed in the form of an aqueous slurry since, in this case particularly, glycerol is effective in aiding the complexing reaction. In addition to glycerol other polyhydroxy compounds such as glycol, propylene glycol, derivatives of glycols such as diethylene, triethylene and the like, erythritol and similar compounds may be employed.

ANTICORROSION AGENTS Although mineral lubricating oils containing the modified sulfonates of this invention, 1. e., the complexes of metal sulfonates with metal salts of weak inorganic acids, have exceptional detergency characteristics it is usually desirable to add to the oil containing the modified sulfonate an agent which will impart anticorrosion characteristics to the oil. Anticorrosion agents which co-operate with the modified sulfonates to produce outstanding lubricating oils having all of the necessary characteristics to permit the use of the oil under severe service conditions in internal combustion engines include the following materials which are known to be anticorrosion agents but which have been found to cooperate with the modified sulfonate of this invention to maintain proper anticorrosion conditions in engines.

One form of anticorrosion agent which may be employed is an oil-soluble metal salt of the acidic reaction products obtained by reacting phosphorus pentasulfide or phosphorus pentoxidc with an alcohol. The preferred reaction products are those obtained with phosphorus pentasulfide. These materials are represented by 011* soluble metal salts of alkyl thiophosphates such as zinc dioctyl dithiophosphate or the corresponding calcium salt or the salt of similar reaction products by the phosphorus pentasulfide and aliphatic alcohols having above about 6 carbon atoms per molecule. Again, similar salts such as the metal salts of the thiophosphate of methylcyclohexyl alcohol may be employed.

Other anticorrosion agents which may be employed in conjunction with the modified sulfonates of this invention include metal salts of phenols and phenol sulfides. These agents may be included in the group of agents which may be referred to as oil-soluble metal salts of high molecular weight non-carboxylic weak acids having ionization constants below about 5X10 Such salts are described in United States Patent No. 2,280,419.

Another class of anticorrosion agents which. may beemployed includes the oil-soluble metal salts formed by reacting phosphorus pentasulfide with hydrocarbons. .Such materials and methods for their preparation are described in United States Patent No. 2,316,082.

Another type of anticorrosion agent which may be employed to impart the desirable anticorrosion characteristics consists of the oil-soluble metal salts of phosphinic or phosphonic acids obtained by treating hydrocarbons with elementary phosphorus and subsequently forming the metal salts of the reaction products. Compounds off this type are described in United States Patent NO. 2,311,305.

Oil-soluble metal salts of the condensation products or resins obtained by reacting a hydrocarbon substituted phenol with a low molecular weight aldehyde such as formaldehyde are outstanding in their ability to co-operate with the modified sulfonates of this invention to produce oils having extremely good anticorrosion and detergency characteristics. These compounds and methods for their preparation are given in United States Patent No. 2,250,188.

Desirable metals to be employed in the preparation of the supplemental oil-soluble metal anticorrosion agents include the alkaline earth metals calciuibarium, strontium and magn sium and the polyvalent metals zinc, aluminum, tin, copper, iron, nickel, mercury and chromium. In some instances alkali metal salts or soaps may be employed, such as the sodium, potassium and lithium compounds, particularly in those instances where the alkali metal (30.1 pounds are sufficiently soluble in oil.

In employing the anticorrosion agents in the order of 1% of the-constituent ordinarily will be adequate, such as 0.5% or 1.0%, or possibly less for some uses. Although not more than-3% or 5% based on the final product is-necessary for most uses, a number of modern heavy duty engines require more, up to 8% or 10%, and amounts up to or more may be desirable for some uses. The anticorrosion agents are conveniently employed in the form of concentrates containing 30to 60% additive dissolved in lubricating oil. They may also be employed in the form of concentrates also containing the modified sulfonates of this invention. In this case, the total additive concentration maybe about 30 to 60%, with the modified sulfonate preferably in slight excess over the anticorrosionagent.

In employing the modified sulfonates above described, the final product obtained is a freely fluid oil possessing no appreciable viscosity increase beyond that of the mineral lubricating oil employed, which mineral oil may be any of the modern types. Normally, the highly refined so-called highly parafiinic lubricating oils will be used, but naphthenic and other parafiinic lubricating oils also are usable. Even in thecase of concentrates containing up to 20% or 30% of the modified soap theconcentrate isstill fluid, does not set up likea grease,.and is readily diluted with additional oil to make the final product. In employing oils containing sulfonates modified by weak acid salts herein described, the detergent action of the oil is improved-up to arating which might be called most excellent as compared with a rating of rather poor where the unmodified sulfonate is used in the same proportion.

In order to show the advantages of employing sulionates modified by the addition of salts of weak inorganic acids in the preparation of lubricating oil compositions, several of the finished oils containing sulfonates modified by the addition thereto of weak acid salts have been compared with oils containing unmodified sulfonates by means of detergency tests carried out in a Lauson single cylinder, standard test engine. In this test, which is referred to as the Lauson engine test, the engine is operated for a total of 60 hours under a, load of about 35 H. P. with a coolant temperature of about 295 F. and an oil temperature of about 280 F. At the end of the test period the cleanliness of the eng ne is observed and given a numerical detergency rating between 0% and 100%, where 100% indicates a perfectly clean engine. Thus, a detergency rating of 100% would indicate that there were substantially no lacquer or varnish-like deposits within the engine. The corrosivity of the oil is determined by the bearing weight loss duri the test run.

Example I A lubricating oil consisting of a solvent treated Western lubricating oil of SAE 30 grade having a viscosity index of 90 which contained 2.0% by weight of calcium sulfonate was found to have a detergency rating of 72% in the Lauson engine test. A lubricant prepared with the same mineral oil containing 2% of the same sulfonate and in which was solubilized about 0.1% by weight of calcium thiosulfate, had a detergency rating of 83%.

Example II In a second comparative test a lubricant prepared with the solvent treated Western oil of Example I containing 1.5% of calcium sulfonate had a detergency rating of 65%. The same composition in which was incorporated 0.2% of calcium arsenate had a detergency rating of 88%.

Example III A portion of the lubricating oil of Example I containing 2.5% by weight of calcium sulfonate was observed to have a detergency rating of '75 whereas a portion of this particular oil in which was incorporated 0.1% of calcium thioarsenate was observed to have a detergency rating of 88%.

Example IV A portion of the Western lubricating oil of Example I containing 2.0% of calcium-sulfonate which had a detergency rating of 72% was compounded with surficient sodium aluminate to give a concentration of approximately 0.3% of the sodium aluminate in the finished oil. This composition had a detergency rating of The following examples serve to illustrate the preparation of various modified sulfonates according to the principles of this invention, which modified sulfonates are found to impart exceptional detergency to the lubricating oils. Moreover, they illustrate the eificacy of these agents alone and in conjunction with anticorrosion agents in producing high quality lubricating oils.

Example V A solution of sodium sulfonate in 2 parts by weight of mineral lubricating oil is heated with an aqueous solution of sodium sulfite to a temperature of 300 F. for a period of two hours. The resultingproduct is filtered hot through filtering clay and added to mineral lubricating oil of the character described in Example I to produce an oil containing 2% by weight of the sodium sulfonate-sodium sulfite complex on an oil-free basis. This product is found to have a detergency rating greater than 85% and is relatively non-corrosive to copper lead bearings as indicated by a small bearing weight loss during engine operation.

Example VI A lead sulfonate concentrate is prepared by treating a 40% by weight solution of sodium sulfonate in oil with an equivalent amount of lead nitrate in aqueous solution. The mixture is heated and agitated at about 150 F. and the resulting lead sulfonate is washed free from inorganic impurities with .water. The lead sulfonate so obtained is mixed with 1 equivalent of lead cyanate and a small amount of water is added. The resulting mixture is heated to a temperature of 350 F. for a period of four hours and then filtered to remove residual insoluble materials. The resulting product has a ratio of equivalents of lead to sulfonic acid of 1.8 to 1.

The oil concentrate of lead sulfonate-lead cyanate is dissolved in a naphthenic Western mineral lubricating oil of SAE grade having a viscosity index of 20 in an amount sufiicient to produce an oil containing 3% by weight of the complex on an oil-free basis. This oil has a detergency rating greater than 88%.

To the above oil containing'the complex is added 1% by weight of the lead salt of paratertiary amyl phenol sulfide. The resulting oil has a detergency rating greater than 88% and is substantially non-corrosive to corrosion-sensitive bearings.

Example VII A barium sulfonate concentrate in oil containing about by weight of barium sulfonate is mixed with 1.5 equivalents of barium pyrophosphate introduced as a slurry in water and heated to a temperature of 350 F. for a period of 2.5 hours. The resulting product is filtered and incorporated in a mineral lubricating oil similar to the one described in Example I in an amount suificient to produce an oil containing 1.5% by weight of the complex on an oil-free basis. The resulting oil has excellent detergency characteristics and when there is added thereto 1.5% by weight of the barium salt of tert-amyl phenolformaldehyde condensation product the resulting oil has not only exceptional detergency but also good anticorrosion characteristics.

E xample VIII Example VII is repeated using an aqueous solution of barium thiocyanate in place of the aqueous slurry of barium pyrophosphate. The resulting lubricating oils containing 1.5% of this complex have detergent and anticorrosion properties similar to the oils of Example VII.

Example IX An aluminum sulfonate concentrate is prepared by treating a 4% by weight solution of sodium sulfonate in oil with an equivalent amount of aluminum nitrate in aqueous solution. The mixture is heated and agitated for about thirty minutes at 159 F. and the resulting aluminum sulfonate is washed free from inorganic impurities with water. The resulting concentrate of aluminum sulfonate in oil is mixed with 1.5 equivalents of calcium metaborate as a slurry in water. This mixture is agitated and heated to a temperature of 350 F. for a period of 3.5 hours and subsequently filtered to remove residual insoluble materials. The resulting product has a ratio of equivalents of metal to sulfonic vacid groups of 2.2 to 1. A lubricating oil containing 5% of this product will have a detergency rating above 84%.

Example X A concentrate of tin sulfonate in oil is prepared by metathesis of a 40% solution of sodium sulfonate in oil with an aqueous stannous chloride solution. The resulting tin sulfonate is water Washed and heated to a temperature of about 350 F. for two hours. The resulting complex after filtration is dissolved in lubricating oil :to produce an oil containing 1% by weight of the complex on an oil-free basis. This oil has a detergency greater than 85%.

Example XI Nickel sulionate is prepared by treating sodium sulfonate in oil solution with an equivalent amount of nickel nitrate in aqueous solution and the resulting nickel sulfonate in oil is water washed and reacted with 2 equivalents of nickel cyanide. The added nickel cyanide is powdered and added as a slurry in water. The mixture is heated to a temperature of 300 F. for four hours with agitation and subsequently filtered. The resulting complex contains a ratio of equivalents of nickel to sulfonic acid groups of about 1.9 to 1. This complex is readily soluble in mineral oil and a lubricating oil containing 2% of the complex has a detergency greater than 85%.

The addition of 1.2% by weight of the nickel salt of the condensation product of tert.-octyl phenol with formaldehyde has a 'detergency above 85% and exhibits exceptional anticorrosion characteristics.

Example XII A beryllium sulfonate-beryllium carbonate complex is prepared in the following manner. Calcium sulfonate in oil solution is metathesized with the chemically equivalent amount of beryllium sulfate in water. This metathesis is carried out using a light petroleum naphtha as a diluent to facilitate removal of precipitated calcium sulfate. The naphtha solution of beryllium sulfonate is separated, washed with water and heated to about 275 F. for about three hours to vaporize the naphtha. The resulting mixture is filtered hot to remove suspended solids and then blown with carbon dioxide for four hours while maintaining a temperature of about 300 F. The resulting beryllium carbonate-beryllium sulfonate complex contains a ratio of equivalents of beryllium to equivalents of sulfonic acid groups of 2 to 1.

A lubricating oil prepared by dissolving the above complex in mineral lubricating oil to produce an oil containing 1.5% by weight of the complex on an oil-free basis has good detergency and anticorrosion characteristics.

Example XIII A sodium sulfonate-sodium carbonate complex is prepared by treating848 parts by weight of commercial sodium sulfonate at a temperature of 300 F. with parts by weight of an aqueous solution containing 50% by weight of sodium hydroxide. The sodium hydroxide is heated over a period of approximately one-half hour and the reaction mass is heated to a temperature of 385 F. and filtered. The clear filtrate is heated to a temperature of 300 F. to 340 F. and anhydrous carbon dioxide passed through the mixture for 2.25 hours. The resulting complex, after filtration, has a ratio of equivalents of sodium carbonate to sodium sulfonate of about 1 to l.

A lubricating oil is prepared by dissolving 8.2% by weight of the sodium sulfonate-sodium carbonate complex in an SAE Western motor oil and tested under standard conditions for a period of 60 hours in a Lauson engine. A bearing weight loss of 265 mg. was noted and the oil was given a detergency rating of 90%.

To the above oil is added 1.7% by weight of the calcium salt of dioctyl dithiophospha'te. The resulting oil has a detergency rating greater than 90% and shows a bearing weight loss in the Lauson engine test of less than 150 mg.

Potassium and lithium complexes correspondin to the above sodium complex and prepared in the same manner impart detergency and anticorrosion characteristics to mineral oil comparable to those obtained with the sodium complex.

Example XIV A zinc sulfonate-zinc borate complex is prepared by heating zinc sulfonate with an aqueous solution of zinc borate (1.2 equivalents) to a temperature of 300 F. in the presence of 4%, based on the zinc sulfonate concentrate, of glycerol. After heating for 1.5 hours the product is filtered. The filtrate, consisting of a zinc sulfonate-zinc borate complex in oil, contains a ratio of equivalents of zinc to sulfonic acid groups of about 2.1 to 1.

The above preparation is found. to require approximately 2.5 hours to 3 hours of heating at the same temperature in order to efiect solubilization of the zinc borate in the absence of glycerol. Using erythritol in place of glycerol solubilization is effected in about the same time as is required employing glycerol.

Example XV A barium sulfonate-sodium phosphate complex is prepared by heating barium sulfonate in oil with 1 equivalent of sodium phosphate in water. To the mixture is added 4% of glycerol, based on the barium sulfonate in oil, and heating is continued for a period of 5 hours at 120 F. During the last 3 hours of the heating period a vacuum is applied to the reaction mixture in order to effect volatilization of the water. At the end of this heating period the mixture is filtered to remove residual insoluble materials and the filtered product contains a ratio of equivalents of metal to sulfonic acid of 1.8 to l.

A lubricating oil containing 7% by weight of the above product is found to have excellent detergency characteristics.

The above description and examples of the invention are not to be taken as limiting since many variations and modifications may be made by those skilled in the art without departing from \the spirit or the scope of the following claims.

I claim:

1. A mineral lubricating oil suitable for use in internal combustion engines containing a minor proportion, sufiicient to impart detergency characteristics to said oil, of a modified oilsoluble metal petroleum sulfonate formed by heating an oil-soluble metal petroleum sulfonate with a metal salt of a weak inorganic acid having an ionization constant less than about 1 10 other than metal oxides, hydroxides, carbonates and bicarbonates, at a temperature sufficient to effect dehydration and to solubilize said weak acid salt in the sulfonate.

2. A mineral lubricating oil suitable for use in internal combustion engines containing a minor proportion, sufiicient to impart detergency characteristics to said. oil, of a modified oil-soluble metal petroleum sulfonate formed by heating an oil-soluble metal petroleum sulfonate in solution in oil with a metal salt of a weak inorganic acid having an ionization constant less than about l 10- other than metal oxides, hydroxides, carbonates and bicarbonates, and water at a temperature between about 120 F. and 500 F. for a time sufficient to insure vaporization of all of the free water.

3. An oil according to claim 2 in which the modified oil-soluble metal petroleum sulfonatc is formed by heating at temperatures between about 200 F. and.450 F.

4.. An oil according to claim 2 in which the oil-soluble metal petroleum sulfonate is a polyvalent metal. sulfonate.

5. An oil according to claim 2 in which said oil-soluble metal petroleum sulfonatc is an alkaline earth metal sulfonate.

6. An oil according to claim 2 in which said oil-soluble metal petroleum sulfonate is an alkali. metal sulfonate.

7. An oil according to claim 2 in which said metal salt of a weak inorganic acid a metal borate.

8. An oil according to claim 2 in which said metal salt of a weak inorganic acid is a polyvalent metal salt.

9. An oil according to claim 2 in which said metal salt of a weak inorganic acid is an alkaline earth metal salt.

10. An oil according to claim 2 in which said metal salt of a weak inorganic acid is an alkali metal salt.

11. A mineral lubricating oil suitable for use in internal combustion engines containing a minor proportion, in the order of about 0.2% to about 5% by weight, on an oil-free basis, of a complex of an oil-soluble metal petroleum fonate with a metal salt of a weak inorganic acid, other than metal oxides, hydroxides, car bonates and bicarbonates, said complex being produced by heating an oil-soluble metal petroleum sulfonate in solution in mineral oil with an inorganic base and adding thereto an amount of a weak inorganic acid having an ionization constant less than about 1 10- other than carbonic acid, suflicient to neutralize said inorganic base thereby roducing an inorganic salt, said heating being effected at temperatures between about 200 F. and 450 F. sufficient to vaporize all of the free water contained in the mixture and yield said complex solubilized in the oil.

12. A mineral lubricating oil suitable for use in internal combustion engines containing a minor proportion, in the order of from about 0.2% to about 20%, of a complex of an oi1-soluble metal petroleum sulfonate and a metal salt of a weak inorganic acid having an ionization constant less than about 1 l0 said complex being produced by admixing an oil-soluble metal petroleum sulfonate in oil solution with between about 5% and based on the metal sulfonate, of a metal salt of a weak inorganic acid having an ionization constant less than about 1 l0- other than metal oxides, hydroxides, carbonates and bicarbonates, at temperatures between about 200 F. and 450 F. sufiicient to dehydrate the mixture, said sulfonate possessing detergent characteristics for resinous and similar deposits formed in internal combustion engines, said salt of a weak inorganic acid having the effect of enhancing the detergent characteristics of the sulfonate.

13. An oil according to claim 12 containing also between 0.5% and 20% by weight of an anticorrosion agent having the eifect of imparting improved anticorrosion characteristics to said oil without decreasing the detergent effect of the metal sulfonate-weak acid salt complex.

14. An oil according to claim 12 containing also between about 0.5% and 20% of an oilsoluble metal salt of an alkyl thiophosphate which is capable of imparting improved anticorrosion characteristics to said 011 without reducing the detergency of said oil.

15. An oil according to claim 13 in which said anticorrosion agent is an oil-soluble metal salt of a hydrocarbon substituted phenol-formaldehyde condensation product.

RICHARD W. MER'I'ES.

14 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A MINERAL LUBRICATING OIL SUITABLE FOR USE IN INTERNAL COMBUSTION ENGINES CONTAINING A MINOR PROPORTION, SUFFICIENT TO IMPART DETERGENCY CHARACTERISTIC TO SAID OIL, OF A MODIFIED OILSOLUBLE METAL PETROLEUM SULFONATE FORMED BY HEATING AN OIL-SOLUBLE METAL PETROLEUM SULFONATE WITH A METAL SALT OF A WEAK INORGANIC ACID HAVING AN IONIZATION CONSTANT LESS THAN ABOUT 1X10-1, OTHER THAN METAL OXIDES, HYDROXIDES, CARBONATES AND BICARBONATES, AT A TEMPERATURE SUFFICIENT TO EFFECT DEHYDRATION AND TO SOLUBILIZE SAID WEAK ACID SALT IN THE SULFONATE. 